re-doing silicone caulk in shower

[dsoniat]

Hey Guys, I really appreciated the help I received from youz guyz a couple years ago as I remodeled my 2 baths. Since then, I've sold that house and built a new one (3 years old now). Having a problem with my new master shower.

The master shower is about 8ft long by about 3 ft deep with a bench all along the 8ft length. The bench is granite top and the tile to granite joint was done with 100% silicone. At one spot the silicone developed a small split and has been leaking moisture under the granite obviously because it had left a dark stain due to being wet.

what I've done:
1. cut and picked out all the silicone (meticulously) with xacto knife.
2. let it dry a couple weeks and put a dehumidifier in there. The "wet" stain has completely disappeared now due to the drying.

I plan to redo the silicone using Mapesil T Plus. I've read all the tutorial at: https://www.johnbridge.com/vbulletin...light=tutorial (Great info!)

Questions:

• Even though I've seemingly cut out and scraped off all the existing silicone, should I rub the edges with a solvent (like acetone) to help eliminate any residue which might inhibit adhesion?
  
• Has anyone used the product Goo Gone for Caulk? Would that be better to use to clean the surfaces?
  
• Also (as per various suggestions in the tutorial) I'm thinking to using either soapy water or denatured alcohol when smoothing the new silicone. I plan to do a test setup to see which one works best for me. Any additional suggestions....?

Thanks for any insight,
David Soniat - now in Port Charlotte, FL

[jadnashua]

What is the width of the gap? A square chunk of silicone doesn't last as long as one shaped more like an hourglass. So, if the gap is wide enough, the use of foam caulk backer rod may help the new stuff last longer. That forces the caulk into the optimal shape, so as things slightly expand and contract, you don't have as much tension on the rectangular block...it has a thin section that stretches better, limiting the tearing potential.

[cx]

Welcome back, David.

A drawing of what I think Jim is recommending.

[dsoniat]

Thanks for the comments guys. to answer the question, the gap is not completely consistent. along it's length, approx one half of it is very tight, and the other half is about 1/8 inch (possibly even 3/16in).

In the wider gap areas, I was already planning on putting in some foam backer rod.

The illustration above makes good sense. But do realize my gap is at change of plane between granite seat and tile on wall behind, but same idea applies.


Anyone have experience with the Goo Gone Caulk remover? Just wondering if that would be useful to help make sure the old silicone is as much cleaned off as possible.

Thanks,
David Soniat - Port Charlotte, FL

[MAPEI - Technical Service]

I have personally never used the Goo Gone product made for caulk before, but have used their other products in the past. Most of them seem to leave a bit of an oily residue, so I would suggest following the Goo Gone product with some sort of alcohol cleaner to make sure that residue (if there is any) is gone before applying the silicone.

Smoothing with soapy water or foaming glass cleaner (my favorite) works very well. The sealant smoothing tools from the big boxes are also nice for getting a consistent final bead.

[dsoniat]

I've used other Goo Gone products in the past which were a bit oily. This doesn't seem to be. the ingredients are:

Product Name: Caulk Remover Product Code: 2066A

Water 7732-18-5 Diluent
Aliphatic ether alcohol 25498-49-1 Solvent
Acetone 67-64-1 Solvent
Benzyl alcohol 100-51-6 Solvent
Modified acrylic polymer Not available Thickener
Triisopropanolamine 122-20-3 Buffer
Fragrance Not available Fragrance
d-Limonene 5989-27-5 Fragrance
Tetrasodium EDTA 64-02-8 Chelating agent
Methylchloroisothiazolinone 26172-55-4 Preservative
Methylisothiazolinone 2682-20-4 Preservative

looks like mostly Acetone and various alcohols. I just did test section. Gonna let dry and make sure it doesn't damage/discolor any of the tile or granite. But it doesn't seem greasy at all.

Thanks,
David Soniat Port Charlotte, FL